Mark, the Dot product does give the result you want,
In[3]:= l1.l2
Out[3]= {20, 49}
Mariusz
>>> On 7/31/2007 at 6:27 AM, in message <f8n2rc$lp9$1 at smc.vnet.net>,
Diamond,
Mark<dot at dot.dot> wrote:
> I have two equi-length lists, the first of number, the second of
> (equi-length) lists of numbers , such as
>
> l1={1,4,3};
> l2={{1,7},{1,9},{5,2}};
>
> I want to produce 1*{1,7}+4*{1,9}+3*{5,2}
>
> It looks so close to Inner that I thought I could use it in some form,
> but I
> have ended up using
>
> (#[[1]]*#[[2]])& /@ Transpose[{l1,l2}]
>
> Is there a better way using one of the builtin functions with which I am
>
> unfamiliar?
>
> Cheers,
>
> Mark Diamond